Persistence of external signs in Pacific herring Clupea pallasii Valenciennes with ichthyophoniasis

Journal of Fish Diseases
By: , and 

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Abstract

The progression of external signs of Ichthyophonus infection in Pacific herring Clupea pallasii Valenciennes was highly variable and asynchronous after intraperitoneal injection with pure parasite preparations; however, external signs generally persisted through the end of the study (429 days post-exposure). Observed signs included papules, erosions and ulcers. The prevalence of external signs plateaued 35 days post-exposure and persisted in 73–79% of exposed individuals through the end of the first experiment (147 days post-exposure). Among a second group of infected herring, external signs completely resolved in only 10% of the fish after 429 days. The onset of mortality preceded the appearance of external signs. Histological examination of infected skin and skeletal muscle tissues indicated an apparent affinity of the parasite for host red muscle. Host responses consisted primarily of granulomatous inflammation, fibrosis and necrosis in the skeletal muscle and other tissues. The persistence and asynchrony of external signs and host response indicated that they were neither a precursor to host mortality nor did they provide reliable metrics for hindcasting on the date of exposure. However, the long-term persistence of clinical signs in Pacific herring may be useful in ascertaining the population-level impacts of ichthyophoniasis in regularly observed populations.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Persistence of external signs in Pacific herring Clupea pallasii Valenciennes with ichthyophoniasis
Series title Journal of Fish Diseases
DOI 10.1111/jfd.12377
Volume 39
Issue 4
Year Published 2016
Language English
Publisher Wiley
Contributing office(s) Western Fisheries Research Center
Description 12 p.
First page 429
Last page 440
Online Only (Y/N) N
Additional Online Files (Y/N) N